hevc/rext: put a warning log message instead of an error log message

cherry picked from commit 243cb99cff727d6a14c32cdff2748f6c255dbaf4
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/hevc_ps.c

@@ -1287,7 +1287,7 @@ int ff_hevc_decode_nal_pps(HEVCContext *s)
         int pps_range_extensions_flag = get_bits1(gb);
         /* int pps_extension_7bits = */ get_bits(gb, 7);
         if (sps->ptl.general_ptl.profile_idc == FF_PROFILE_HEVC_REXT && pps_range_extensions_flag) {
-            av_log(s->avctx, AV_LOG_ERROR,
+            av_log(s->avctx, AV_LOG_WARNING,
                    "PPS extension flag is partially implemented.\n");
             pps_range_extensions(s, pps, sps);
         }